Title: Searching for the Coolest Brown Dwarfs in the Solar Neighborhood

Abstract: Brown dwarfs (BDs) provide a natural link between the physics of stars and gas giant planets. Although hundreds of BDs have been discovered to date, a gap of nearly 400 K remains between the coolest BDs known (\teff ~ 500 K) and Jupiter (\teff ~ 128 K). Detailed studies of these cool BDs will allow us to measure the low-mass mass function and extend our studies of low-temperature, high-pressure atmospheric physics and chemistry well into the exoplanet regime. One of the primary science goals of the Wide-field Infrared Survey Explorer (WISE), a NASA MIDEX mission to survey the entire sky at 4 mid-infrared wavelengths, is to identify such cool BDs. We propose to obtain YJHK spectra of WISE BD candidates with the Gemini Near-Infrared Spectrograph (GNIRS). The proposed observations will allow us 1) to characterize the spectral and physical properties of the BDs and 2) improve our candidate selection by providing important feedback on our search criteria. The majority of BDs discovered with WISE will have 17.5 < J <19.5 making the proposed GNIRS observations central to our northern hemisphere WISE BD followup campaign.